1. Field of the Invention
This invention relates generally to a waveguide parametric device that provides relatively high laser power in the wavelength range from the visible to the mid-wave infrared (MWIR) and, more particularly, to a multi-mode waveguide parametric device that generates an output beam at these wavelengths by providing quasi-phase matching between a signal beam and a pump beam, where the parametric device includes alternating oppositely orientated layers having a periodicity that provides the quasi-phase matching only for fundamental mode propagation.
2. Discussion of the Related Art
There is a significant need for a high power mid-wave infrared (MWIR) laser source for both military and industrial applications. For example, heat seeking missiles typically have a detector that detects mid-wave infrared wavelengths, particularly 3-6 μm, as a target. An MWIR laser source could provide an infrared counter measure by directing a beam from the source into the detector of the missile. Further, laser radar applications (LADAR) in the mid-wave infrared wavelengths are able to effectively penetrate moisture in the air, thus making them an all weather radar solution. Other applications for MWIR laser sources include atmospheric laser remote sensing and material processing. Additionally, a similar need exists for high power sources of visible and near infrared (NIR) wavelengths. For example, visible blue green wavelengths propagate well in ocean water, enabling detection of underwater mines or communicating with submerged submarines, and high power NIR beams are useful for LADAR and remote sensing.
It is known in the art to provide an MWIR laser source that generates a laser beam in the mid-wave infrared frequency range. However, there are significant design challenges for providing an MWIR laser source that generates mid-wave infrared wavelengths at high power. One approach for high power applications is to generate a laser beam that is not in the mid-wave infrared frequency range, and then use a non-linear conversion process, such as difference frequency generation (DFG), with appropriate phase matching to convert the laser beam to the mid-wave infrared frequencies. However, such a conventional solution is proven to be costly and relatively ineffective. Similarly, conventional high power sources for the visible or NIR employing second harmonic generation (SHG) or optical parametric amplification (OPA) are known to encounter serious performance limitations.
As is known in the art, single mode waveguides typically provide the best quality laser beam at a particular frequency band. As the size of the waveguide increases, however, more modes are typically generated, which reduces the brightness and quality of the beam. Technological advances in optical waveguide design and operation have allowed the size of the waveguide to increase and still provide for single mode beam propagation.